Cartridge-type electrostatic paint applicators are known as being suitable for use with electrically conductive paints such as water-borne paints and metallic paints. Patent documents 1 to 3 disclose cartridge-type electrostatic paint applicators. These cartridge-type electrostatic paint applicators make it easy to prevent high-voltage leak, which is the phenomenon that a high voltage applied to an electrostatic applicator externally leaks through an electrically conductive paint.
A typical cartridge-type electrostatic applicator has a paint cartridge detachably attached to a rear end of the main body of the electrostatic paint applicator. The paint cartridge contains an electrically conductive paint. When the paint in the paint cartridge is exhausted, the cartridge is replaced by a new paint cartridge containing a predetermined quantity of paint.
Patent Document 1 proposes the use of a paint bag containing a paint and an actuating bag receiving an actuating liquid, both accommodated in a paint cartridge case, such that the actuating bag swells out when it is supplied with the actuating liquid through a conduit extending in a robotic arm. The actuating bag thereby pushes the paint bag to extrude the paint out of the paint bag. The outflow quantity of the paint from the paint bag can be controlled by adjusting the quantity of the actuating liquid supplied to the actuating bag.
Similarly to Patent Document 1, Patent Document 2 proposes the use of a paint bag and an actuating bag accommodated in a paint cartridge case, such that the actuating bag squeezes the paint bag when swelling out with an actuating liquid supplied through a conduit extending in a robotic arm. This Patent Document 2 also proposes partly binding contact surfaces of the paint bag and the actuating bag with each another to prevent positional deviation between contact surfaces of the paint bag and the actuating bag.
Patent Document 3 proposes to accommodate a paint bag in a case of a paint cartridge and squeezing the paint bag by supplying an actuating liquid into the space inside the case through a conduit extending in a robotic arm. This patent document also proposes to make the case of a transparent material such that any trouble in the case can be found easily.
The paint cartridges disclosed by the Patent Documents 1 to 3 have both a paint port for passage of the paint and an actuating liquid port for passage of the actuating liquid at the bottom of the case.
The aforementioned cartridge-type electrostatic paint applicators are actually used for coating vehicle bodies. It is known that coating robots are conveniently used for electrostatic coating of vehicles.
Patent Document 4 proposes a system for exchanging a paint cartridge. This cartridge exchanging system comprises a stock mechanism for stocking an empty paint cartridge, a paint refill mechanism for refilling the empty paint cartridge, and a cartridge exchanging mechanism for transporting the paint cartridge to and from the coating robot. The cartridge exchanging mechanism includes a handling means for clutching the paint cartridge. The handling means is movable vertically and horizontally.
The handling means picks up an empty paint cartridge heretofore stocked in the stock mechanism, then transports it to a paint refill position, and puts down the paint cartridge at the paint refill position. Simultaneously, the refill mechanism moves up, and couples with the paint port at the bottom of the paint cartridge. The paint refill mechanism refills the paint cartridge (paint bag) with a predetermined amount of paint through the paint port. After the refill of the paint, the paint refill mechanism withdraws downward. The electrostatic paint applicator attached to the coating robot is brought at a predetermined exchange position by a movement of the coating robot. Then, the handling means rotates horizontally to transport the paint cartridge, now refilled with the paint, to the exchange position, and next moves down to connect the paint port and the actuating liquid port at the bottom of the paint cartridge to corresponding ports of the electrostatic paint applicator.
Patent Document 1: JP 2005-87810 A
Patent Document 2: JP 2005-296750 A
Patent Document 3: JP 2006-347606 A
Patent Document 4: JP 2006-341192 A